The invention relates to a hydraulic motor having a non-rotating annular outer casing, moving eccentric means inside the outer casing, a power shaft connected to the eccentric means and rotatable thereby, a pressure chamber arrangement communicating with the eccentric means for moving the eccentric means and thus rotating the power shaft by means of hydraulic fluid, steam or pressurized air led into and removed from the pressure chamber arrangement, and a non-rotating annular inner casing inside the non-rotating annular outer casing.
In principle, hydraulic motors are the opposite of hydraulic pumps. They change hydraulic energy back to mechanical energy. In structure, hydraulic motors greatly resemble pumps and sometimes it is possible to use a hydraulic pump as a motor and vice versa. The matter should, however, be checked with the manufacturer of the pump or motor. Hydraulic motors work like pumps, i.e. using the displacement principle. The motors are controlled in an open hydraulic system by 4-way valves or a closed hydraulic system is used. In many cases, the motor can be made rotate in both directions. High torques and outlets with respect to their size characterize hydraulic motors. The start-up torques are 80 to 99% of the rated torque. The motors are well suited for demanding conditions, because the hydraulic system is tight and the heat generated in the motor is transmitted with a medium to a container. Hydraulic motors often have a separate leak connection that is connected to the container. The motors are either slow-speed 0 to 500 r/min (high torque) or high-speed 1,000 to 4,000 r/min (low torque). The most common hydraulic motor types are: gear motor, vane motor and piston motor.
This invention relates to vane motors. In known vane motors, a non-rotating stator forms the outer circumference of the motor. Inside the stator, there is a round chamber mounted with an eccentric rotor. The rotor has vanes at regular intervals that are sealed against the inner ring of the stator forming chambers between the stator and rotor. Pressurized hydraulic fluid is fed from one side of the stator to these chambers and correspondingly, the hydraulic fluid is removed from the other side of the stator, whereby the rotor is made to rotate. Known vane motors can be constant or adjustable in displacement. The adjustment is done by altering the eccentricity of the rotor. At low speeds of rotation, the pushing out of the vanes is ensured by means of springs. Vane motors are generally high-speed motors. Slowly rotating high-torque motors have also been constructed of them by increasing the rotor width by increasing the diameter and by adding pressure chambers, whereby the displacement can be increased.
Drawbacks with this and all other prior-art hydraulic motors include friction and wear problems of the rotating parts and the limited rotating rate, outlet and torque caused by this.